1. Field of the Invention
This invention relates to the field of networking. In particular, the invention relates to prioritizing and queuing updated routing information.
2. Description of the Related Art
Internetworks such as the Internet currently comprise Autonomous Systems, which exchange routing information via exterior gateway protocols. Amongst the most important of these protocols is the Border Gateway Protocol, or BGP. BGPv4 constructs a directed graph of the Autonomous Systems, based on the information exchanged between BGP routers. Each Autonomous System in identified by a unique 16 bit AS number, and, by use of the directed graphs, BGP ensures loop-free routing amongst the Autonomous Systems; BGP also enables the exchange of additional routing information between Autonomous Systems. BGP is further described in several RFCs, which are compiled in The Big Book of Border Gateway Protocol RFCs, by Pete Loshin, which is hereby incorporated by reference.
The Border Gateway Protocol provides network administrators some measure of control over outbound traffic control from their respective organizations. For instance, the protocol includes a LOCAL_PREF attribute, which allows BGP speakers to inform other BGP speakers within the Autonomous System of the speaker's preference for an advertised route. The local preference attribute includes a degree of preference for the advertised route, which enables comparison against other routes for the same destination. As the LOCAL_PREF attribute is shared with other routers within an Autonomous System via IBGP, it determines outbound routes used by routers within the Autonomous System.
A WEIGHT parameter may also be used to indicate route preferences; higher preferences are assigned to routes with higher values of WEIGHT. The WEIGHT parameter is a proprietary addition to the BGPv4 supported by Cisco Systems, Inc. of San Jose, Calif. In typical implementations, the WEIGHT parameter is given higher precedence than other BGP attributes.
The performance knobs described above are, however, rather simple, as they do not offer system administrators with sufficiently sophisticated means for enabling routers to discriminate amongst routes. There is a need for technology that enables greater control over outbound routing policy. In particular, there is a need to allow performance data about routes to be exchanged between routers. Additionally, system administrators should be able to fine tune routing policy based upon sophisticated, up-to-date measurements of route performance and pricing analysis of various routes.